HP 5520 All-In-One black ink won't print

I recently replaced the 564 black cartridge with a new one and noticed that anything that was supposed to print in black either didn't print or came out spotty or very faded looking. Thiking that I had a bad cartridge, I went and got a new one and installed that today - only to have the same problem.

I've cleaned the print heads mulitple times, re-aligned the printer, made sure the vents on the tops of the cartridge are clean, and verified that it's seated correctly in the ink carriage.

I have no idea why this is happening and I'm out $50 in ink so far, which is fast adding up.

If not though, please let me know whether your printer is still under warranty or not as well as what country you're in and I'll make sure this gets resolved for you! Please feel free to private message me the country information if you don't want to post it on the forums.